根据龙门山前陆盆地西缘沉降中心、冲积扇侧向迁移、活动构造地貌和古地磁等标志及龙门山在中生代以来的走滑作用和走滑方向的标定研究,结果表明:龙门山断裂带具有走滑性质,走滑方向曾发生过反转,在反转之前以左行走滑作用为特征,在反...根据龙门山前陆盆地西缘沉降中心、冲积扇侧向迁移、活动构造地貌和古地磁等标志及龙门山在中生代以来的走滑作用和走滑方向的标定研究,结果表明:龙门山断裂带具有走滑性质,走滑方向曾发生过反转,在反转之前以左行走滑作用为特征,在反转之后以右行走滑作用为特征。根据地层记录和古地磁证据,认为龙门山走滑方向反转的时间应介于43 M a^3.6 M a之间,即由中生代至早新生代时期的左行走滑作用反转为晚新生代时期的右行走滑作用。然对龙门山断裂带走滑方向反转的成因初步分析认为晚新生代龙门山右行走滑作用是印-亚碰撞后构造作用的产物,晚三叠世至早新生代左行走滑作用是青藏高原自晚三叠世以来大陆碰撞作用导致松潘-甘孜褶皱带北东-南西向缩短的产物。展开更多
In this paper, a new method of time reversal for defect diagnosis of concealed structure has been proposed based on the detecting technique of structure acoustic wave and the theory of time reversal. The time reversal...In this paper, a new method of time reversal for defect diagnosis of concealed structure has been proposed based on the detecting technique of structure acoustic wave and the theory of time reversal. The time reversal recurrence formula for detecting the acoustic wave speed constitution of concealed structures with bilevel asynchronous test has been established. The wave speed constitution can be reconstructed in 2 D graticule form by means of this method. The result of model test shows the method is valid.展开更多
Typical existing methods of tunnel geological prediction include negative apparent velocity, horizontal seismic profile, and the Tunnel Seismic Prediction （TSP） method as this technology is under development at home...Typical existing methods of tunnel geological prediction include negative apparent velocity, horizontal seismic profile, and the Tunnel Seismic Prediction （TSP） method as this technology is under development at home and abroad. Considering simpler observational methods and data processing, it is hard to accurately determine the seismic velocity of the wall rock in the front of the tunnel face. Therefore, applying these defective methods may result in inaccurate geological inferences which will not provide sufficient evidence for classifying the wall rock characteristics. This paper proposes the Tunnel Seismic Tomography （TST） method using a spatial observation arrangement and migration and travel time inversion image processing to solve the problem of analyzing the velocity structure of wall rock in the front of the tunnel face and realize accurate imaging of the geological framework of the tunnel wall rock. This method is very appropriate for geological prediction under complex geological conditions.展开更多
The fi rst arrival waveform inversion(FAWI)has a strong nonlinearity due to the objective function using L2 parametrization.When the initial velocity is not accurate,the inversion can easily fall into local minima.In ...The fi rst arrival waveform inversion(FAWI)has a strong nonlinearity due to the objective function using L2 parametrization.When the initial velocity is not accurate,the inversion can easily fall into local minima.In the full waveform inversion method,adding a cross-correlation function to the objective function can eff ectively reduce the nonlinearity of the inversion process.In this paper,the nonlinearity of this process is reduced by introducing the correlation objective function into the FAWI and by deriving the corresponding gradient formula.We then combine the first-arrival wave travel-time tomography with the FAWI to form a set of inversion processes.This paper uses the limited memory Broyden-Fletcher-Goldfarb-Shanno(L-BFGS)algorithm to improve the computational effi ciency of inversion and solve the problem of the low effi ciency of the FAWI method.The overthrust model and fi eld data test show that the method used in this paper can eff ectively reduce the nonlinearity of inversion and improve the inversion calculation effi ciency at the same time.展开更多
The static correction of a near-surface model may be improved by using travel time tomographic inversion.We discuss unfavorable factors in the inversion of surface seismic waves that have been analyzed by the first br...The static correction of a near-surface model may be improved by using travel time tomographic inversion.We discuss unfavorable factors in the inversion of surface seismic waves that have been analyzed by the first break.These factors show that sources and geophones arranged on the surface,or close to the surface,give a first break that only includes the direct wave and the up going wave from the down going to up going transition.These up going waves have weak directivity when they arrive at a geophone and so the rays passing through the grids have small directional differences and a narrow azimuth.Drawing lessons from the advantages of Vertical Seismic Profiling(VSP) acquisition mode we describe a pseudo well-surface simultaneous travel time tomographic inversion of a near-surface model.The well depth should be increased in the surface seismic study to produce a pure up going wave,to enhance the verticality of the rays and to increase the azimuth and shorten path length of the rays.Simulations of the effect of well depth on a pseudo well-surface simultaneous travel time tomographic inversion model are reported.The results show that the static corrections are improved significantly when the well depth extends below the weathered or sub-weathered layers.The root mean square error of the statics is 1.14 or 0.93 ms for these two situations,respectively.展开更多
Objective Endogenous nitric oxide （NO） has been implicated in the regulation of neuronal activity which mediates cardiovascular reflexes. However, there is controversy concerning the role of NO in the nucleus tractu...Objective Endogenous nitric oxide （NO） has been implicated in the regulation of neuronal activity which mediates cardiovascular reflexes. However, there is controversy concerning the role of NO in the nucleus tractus solitarius （NTS）. The present study aims to elucidate the possible physiological role of endogenous NO in modulating the excitatory vagal afferent input to NTS neurons. Methods All the experiments in the rat were conducted under anaesthetic conditions. Ionophoresis method was used for the application of NO donor or nitric oxide synthase （NOS） inhibitor, and single unit recording method was employed to detect the effects of these applications on vagal afferentor cardio-pulmonary C-fibre reflex-evoked neuronal excitation in NTS. Results Ionophoresis applications of L-arginine （L-Arg）, a substrate of NOS, and sodium nitroprusside （SNP）, a NO donor, both attenuated the vagal afferent-evoked discharge by （51.5±7.6）% （n = 17） and （68.3±7.1）% （n = 9）, respectively. In contrast, application of D-Arg at the same current exerted no overall effect on this input. Also, both L-Arg and SNP inhibited spontaneous firing of most of the recorded neurons. In contrast, ionophoresis application of NG-nitro-Larginine methyl ester （L-NAME） enhanced vagal afferent-evoked excitation by （66.3±11.4）% （n = 7）. In addition, ionophoresis application of L-Arg and SNP significantly attenuated cardio-pulmonary C-fibre reflex-induced excitation in the tested NTS neurons. Conclusion Activation of local NO pathway in the NTS could suppress vagal afferent-evoked excitation, suggesting that NO is an important neuromodulator of visceral sensory input in the NTS.展开更多
文摘根据龙门山前陆盆地西缘沉降中心、冲积扇侧向迁移、活动构造地貌和古地磁等标志及龙门山在中生代以来的走滑作用和走滑方向的标定研究,结果表明:龙门山断裂带具有走滑性质,走滑方向曾发生过反转,在反转之前以左行走滑作用为特征,在反转之后以右行走滑作用为特征。根据地层记录和古地磁证据,认为龙门山走滑方向反转的时间应介于43 M a^3.6 M a之间,即由中生代至早新生代时期的左行走滑作用反转为晚新生代时期的右行走滑作用。然对龙门山断裂带走滑方向反转的成因初步分析认为晚新生代龙门山右行走滑作用是印-亚碰撞后构造作用的产物,晚三叠世至早新生代左行走滑作用是青藏高原自晚三叠世以来大陆碰撞作用导致松潘-甘孜褶皱带北东-南西向缩短的产物。
基金financially supported by projects from the National Natural Science Foundation of China(No.41941016,42020104007)Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(GML2019ZD0201)+2 种基金the Ministry of Science and Technology of China(No.2021FY100101,2019QZKK0901)the China Geological Survey(No.DD20221630)Institute of Geology,Chinese Academy of Geological Sciences(No.J2107,J2201)。
文摘印度-亚洲碰撞后,大陆板块沿着大型的左行走滑断裂挤出。规模最大的哀牢山-红河剪切带(ASRR)将印支地块(巽他地块)与华南地块分隔开来。长约1000 km的红河活动断裂(RRF)沿哀牢山的北侧延伸,目前呈现出右行走滑兼正断的活动性质。本文在讨论了红河断裂系及其周缘的第三纪和现今变形特征(滑移性质反转、渐新世/第四纪位错、全新世滑动速率、GPS测量、地震机制等)基础之上,重点论述了其在上新世—第四纪从云南东南部到越南西北部、北部湾西部、再到更南的沙巴地区的断裂分布和运动学特征。新的数据证实,跨过三联点和越南西北部的奠边府断层之后,华南地块与巽他地块之间的现今大部分右行走滑主要沿着Da River断裂向Day Nui Con Voi(或称大象山)东南方向延伸。Da River断裂与RRF大致平行,是2020年M_(w) 5.0莫州地震的发震断层。进一步研究表明,Da River断裂很可能沿着渐新世—中新世莺歌海/宋红盆地西缘和越南东南海岸(归仁剪切带)向南延伸得更远,至少延伸到“Ile des Cendres”火山群,并可能继续延伸到沙巴-文莱逆冲带的西端,靠近婆罗洲北部的近海活动边缘。最后,我们讨论了在菲律宾群岛、台湾岛和巽他群岛之间南海大部分地区大规模构造反转的运动学效应。
文摘In this paper, a new method of time reversal for defect diagnosis of concealed structure has been proposed based on the detecting technique of structure acoustic wave and the theory of time reversal. The time reversal recurrence formula for detecting the acoustic wave speed constitution of concealed structures with bilevel asynchronous test has been established. The wave speed constitution can be reconstructed in 2 D graticule form by means of this method. The result of model test shows the method is valid.
文摘Typical existing methods of tunnel geological prediction include negative apparent velocity, horizontal seismic profile, and the Tunnel Seismic Prediction （TSP） method as this technology is under development at home and abroad. Considering simpler observational methods and data processing, it is hard to accurately determine the seismic velocity of the wall rock in the front of the tunnel face. Therefore, applying these defective methods may result in inaccurate geological inferences which will not provide sufficient evidence for classifying the wall rock characteristics. This paper proposes the Tunnel Seismic Tomography （TST） method using a spatial observation arrangement and migration and travel time inversion image processing to solve the problem of analyzing the velocity structure of wall rock in the front of the tunnel face and realize accurate imaging of the geological framework of the tunnel wall rock. This method is very appropriate for geological prediction under complex geological conditions.
基金supported by the Major Scientific and Technological Project of PetroChina (ZD2019-183-003)Project of National Natural Science Foundation of China (42074133)+1 种基金the Fundamental Research Funds for the Central Universities (19CX02056A)Project of State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development (33550000-21-FW0399-0009)
文摘The fi rst arrival waveform inversion(FAWI)has a strong nonlinearity due to the objective function using L2 parametrization.When the initial velocity is not accurate,the inversion can easily fall into local minima.In the full waveform inversion method,adding a cross-correlation function to the objective function can eff ectively reduce the nonlinearity of the inversion process.In this paper,the nonlinearity of this process is reduced by introducing the correlation objective function into the FAWI and by deriving the corresponding gradient formula.We then combine the first-arrival wave travel-time tomography with the FAWI to form a set of inversion processes.This paper uses the limited memory Broyden-Fletcher-Goldfarb-Shanno(L-BFGS)algorithm to improve the computational effi ciency of inversion and solve the problem of the low effi ciency of the FAWI method.The overthrust model and fi eld data test show that the method used in this paper can eff ectively reduce the nonlinearity of inversion and improve the inversion calculation effi ciency at the same time.
文摘The static correction of a near-surface model may be improved by using travel time tomographic inversion.We discuss unfavorable factors in the inversion of surface seismic waves that have been analyzed by the first break.These factors show that sources and geophones arranged on the surface,or close to the surface,give a first break that only includes the direct wave and the up going wave from the down going to up going transition.These up going waves have weak directivity when they arrive at a geophone and so the rays passing through the grids have small directional differences and a narrow azimuth.Drawing lessons from the advantages of Vertical Seismic Profiling(VSP) acquisition mode we describe a pseudo well-surface simultaneous travel time tomographic inversion of a near-surface model.The well depth should be increased in the surface seismic study to produce a pure up going wave,to enhance the verticality of the rays and to increase the azimuth and shorten path length of the rays.Simulations of the effect of well depth on a pseudo well-surface simultaneous travel time tomographic inversion model are reported.The results show that the static corrections are improved significantly when the well depth extends below the weathered or sub-weathered layers.The root mean square error of the statics is 1.14 or 0.93 ms for these two situations,respectively.
基金supported by Chongqing Science and Technology Commission (No.CHTC2007BA5025)Shanghai Pujiang Program (No.07PJ14015)Chongqing Educational Department (No. KJ0707021)
文摘Objective Endogenous nitric oxide （NO） has been implicated in the regulation of neuronal activity which mediates cardiovascular reflexes. However, there is controversy concerning the role of NO in the nucleus tractus solitarius （NTS）. The present study aims to elucidate the possible physiological role of endogenous NO in modulating the excitatory vagal afferent input to NTS neurons. Methods All the experiments in the rat were conducted under anaesthetic conditions. Ionophoresis method was used for the application of NO donor or nitric oxide synthase （NOS） inhibitor, and single unit recording method was employed to detect the effects of these applications on vagal afferentor cardio-pulmonary C-fibre reflex-evoked neuronal excitation in NTS. Results Ionophoresis applications of L-arginine （L-Arg）, a substrate of NOS, and sodium nitroprusside （SNP）, a NO donor, both attenuated the vagal afferent-evoked discharge by （51.5±7.6）% （n = 17） and （68.3±7.1）% （n = 9）, respectively. In contrast, application of D-Arg at the same current exerted no overall effect on this input. Also, both L-Arg and SNP inhibited spontaneous firing of most of the recorded neurons. In contrast, ionophoresis application of NG-nitro-Larginine methyl ester （L-NAME） enhanced vagal afferent-evoked excitation by （66.3±11.4）% （n = 7）. In addition, ionophoresis application of L-Arg and SNP significantly attenuated cardio-pulmonary C-fibre reflex-induced excitation in the tested NTS neurons. Conclusion Activation of local NO pathway in the NTS could suppress vagal afferent-evoked excitation, suggesting that NO is an important neuromodulator of visceral sensory input in the NTS.
